Called 5by, StumbleUpon’s new iOS app is designed to let users, well, stumble upon videos that might be of interest to them.

5by is basically a video concierge service that sifts through the mountains of videos available online, and creates custom playlists based not just on your mood and interests, but also the time of day and the length of time you have available for viewing.

Whether you’re at work and want to watch videos on your lunch break, or looking for a dinner recipe while waiting for the bus, 5by can pull up relevant content.

Making the system more useful it that it grows and learns with the user over time — as your response to recommendations are used to fine-tune the recommender process.

About the author

Luke Dormehl is a UK-based journalist and author, with a background working in documentary film for Channel 4 and the BBC. He is the author of The Formula: How Algorithms Solve All Our Problems, And Create More and The Apple Revolution, both published by Penguin/Random House. His tech writing has also appeared in Wired, Fast Company, Techmeme, and other publications. He'd like you a lot if you followed him on Twitter.

(sorry, you need Javascript to see this e-mail address) | Read more posts by Luke Dormehl.